Cheese curd composition

Typically, five steps, or groups of steps, are involved in the conversion of milk to cheese curd coagulation, acidification, syneresis (expulsion of whey), moulding/shaping and salting. These steps, which partly overlap, enable the cheesemaker to control the composition of cheese, which, in turn, has a major influence on cheese ripening and quality. 

Fat is a major component in most cheese types, but its level and importance differ markedly with variety. Inter- and intra-variety differences in fat content are affected by a number of factors, including milk composition (particularly ratio of protein to fat), and the cheesemaking process (recipe, manufacturing procedure and technology), which control the levels of milk fat and moisture retained in the cheese curd and the moisture content of the cheese. The ratio of protein-to-fat in the cheese milk is probably the principal factor influencing fat content, as it controls the relative proportions of two of the three major compositional components in cheese, namely protein and fat the third major component is moisture. Owing to the inverse relationship between the percentage of moisture and fat in cheese, as discussed in Section... 

C. Cheese Science and Technology Composition and Constituents of Milk Conversion of Milk to Cheese Curd... 

Milk contains 3.3% total protein. There are two major categories of milk protein that are broadly defined by their chemical composition and physical properties. The casein family contains phosphorus and will coagulate or precipitate at pH 4.6. The serum [whey] proteins do not contain phosphorus, and these proteins remain in solution in milk at pH 4.6. The principle of coagulation, or curd formation, at reduced pH is the basis for cheese curd formation. In cow s milk, approximately 82% of milk protein is casein and the remaining 18% is serum, or whey protein. 

Whey is the fluid obtained by separatiag the coagulum from cream and/or skim milk, and is a by-product of either caseia or cheese manufacture. The composition of whey is determined by the method of curd formation, curd handling practices, and methods of handling whey as it is separated from the curd. Dried acid whey contains ca 12.5 wt % proteia (total nitrogea x6.38), 11.0 wt % ash, and 59 wt % lactose, whereas sweet whey contains 13.5 wt % proteia, 1.2 wt % fat, 8.4 wt % ash and 74 wt % lactose. The composition varies with the type of acid used (7). 

To increase curd elasticity and improve eye formation, the milk used to produce Swiss cheese must be clarified. Standardization of the fat content of the milk after clarification ensures uniform composition. Rennet and lactic acid from the bacteria cause casein coagulation. Swiss cheeses made in the United States are cured for three to four... 

Guinee, T.P., Fenelon, M.A., Mulholland, E.O., O Kennedy, B.T., O Brien, N., Reville, W.J. 1998. The influence of milk pasteurization temperature and pH at curd milling on the composition, texture and maturation of reduced-fat Cheddar cheese. Int. J. Dairy Technol. 51, 1-10. 

Lee et al. (32) investigated the potential for utilizing NIRS to rapidly determine composition of curds during cheese making. The authors reported that an acceptable linear relationship was found between chemical and NIRS analysis and that the standard deviation for NIRS measurements was lower than that for the chemical values for all the constituents. 

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